3.0 Low oil pressure problem

[regal17]

Hey guys I have a mercruiser 3.0 with an oil pressure issue. started at the unit and tested the gauge which is functioning. I just replaced the sending unit due to the amount of corrsion the was on the underside of it. Now when out running the boat I had steady pressure up to 3000 rpm then after it nearly dropped to 0 when running full throttle. I cut back when I saw the issue and limped back to dock. I checked the oil and seems very runny and has a fuel smell. no milky oil whatsoever. I read to check the fuel pump diaphram so I pulled the pump and had a good look at it which has no rupture signs and the clear tube going from pump to carb is clear. I'm thinking im losing pressure because of my oil being thinned out by fuel. the other culprit may be the carb?? the boat wants to fall on it's face during acceleration also. compression test solid across the board. Has this happened to anyone before?? just looking to get pointed in the right direction.
Thanks in advance guys!!!!

 

[Don S]

Re: 3.0 Low oil pressure problem

Hook up a mechanical gauge (Not electric) and find out what the oil pressure really is.

 

[Bondo]

Re: 3.0 Low oil pressure problem

Hook up a mechanical gauge (Not electric) and find out what the oil pressure really is.

Ayuh,.... 'n if the oil smells like gas,.... Change it 1st....

 

[regal17]

Re: 3.0 Low oil pressure problem

Right after I posted this I went and put a gauge up to it reading 35-40 at idle and dropping from there to 1-3 at WOT. again shut it down limped to dock. guess my gauge on the dash is right . hmmmm

 

[regal17]

Re: 3.0 Low oil pressure problem

Would gas in oil cause higher or lower oil pressure?

 

[Don S]

Re: 3.0 Low oil pressure problem

Too much oil can do that, and yes gas in the oil will also increase the oil lever. When the level is high enough to hit the crankshaft, the crankshaft will aerate the oil, at that point the pump can't compress air and the oil pressure drops and the lifters start collapsing and the engine gets noisy and not running right.
Another prop with a lot of gas is if it ignites and explodes.